Resistance coupled high frequency amplifier



Jan. 5,1937. M. VON ARDENNE 2,066,751

v RESISTANCE COUPLED HIGH FREQUENCY AMPLIFIER Filed May 4, 1929 2 Sheets-Sheet 1 Jan. 5, 1937.

' M. VON ARDENNE RESISTANCE COUPLED HIGH FREQUENCY AMPLIFIER- Filed My'4, 1929 2 Sheets-Sheet 2 Patented Jan. 5, 1937 UNITED STATES PATENT OFFICE RESISTANCE COUPLED HIGH FREQUENCY AMPLIFIER.

Manfred von Ardenne, Berlin, Germany, assignor to Radioaktiengesellschaft. D. S. Loewe, Berlin- Steglitz, Germany, a company of Germany Application May 4, 1929, Serial No. 360,480 In Germany May 5, 1928 5 Claims. (01. 179-471 Another object is to provide means as to pre-' vent every self-excitation of the amplifier.

Other objects and advantages of the invention will be made apparent upon reading the following description.

The invention consists substantially in the dimension, combination, location and relative arrangement of parts all as will be more fully hereinafter set forth as shown by the accompanying drawings and finally pointed out in the appended claims. 7 p i In accordance with my invention I employ multiple valves wherein the injurious capacities can be made so small that a good high frequency power amplification ratio may be obtained for every system. v

Further I provide suitably dimensioned coupling elements, particularly grid blocking .condensers, whereby a much inferior low frequency power amplification ratio of the high frequency amplification may be obtained when using high frequency amplification.

The high frequency repeater circuit according to the invention allows an undisturbed series connection of some high frequency amplification stages e. g. 4 or 6, the provided means preventing every self-excitation merely by an appropriate screening.

The coupling elements of the single high frequency amplifier valves are dimensioned with anode resistances of 2,000 to 100,000 ohms and grid leak resistances of 6,000 to 300,000 ohms with coupling condensers in the order of less than 200 c. m. whereby it is reached that its capacitive resistance is small compared to the grid circuit resistance of the next valve, whereas its capacitive resistance of low frequency is very large compared to the grid circuit resistance of the next valve.

According to the invention the high frequency amplifier may be built up of separate valves at best in using special high frequency Valves in avoiding carefully the injurious capacities of particular valves but it may also be built up with great advantage of high frequency multiple valves, whereby it is suitable to join twosystems in one valve because having two systems, no self-excitation may appear. It is advantageous to screen metallically every valve or every group of valves and to connect the screening with the heating circuit or with the earth.

Particular advantages are the good selectivity of the high frequency amplifier which is reached by the fact that the tuned receiver circuit is coupled loose with an aperiodical input circuit of the high frequency amplifier, whereby the selfinduction of the output circuit, which consists of one coil only, is selected so that its dimension is adapted to the range of frequencies which is to be received. In the output circuit of the high frequency amplifier there is arranged only one coil, too, which is coupled with the tuned input circuit to the rectifier and the low-frequency amplifier. The self-induction of the coil is selected smaller than that of the coil of the input-circuit.

For regulating the intensity of sound in the most suitable way of the high frequency amplifier a controlling resistance is arranged in the filament circuit of the last high frequency valve or in the multiple valve, which allows in the suitable way, without producing disturbing noises, to change the intensity of sound in the great range by displacing the working point on the characteristic of the valve.

My invention may be best understood with reference to the accompanying drawings, wherein Fig. 1 is a schematic drawing of the invention, and Fig. 2 is the wiring diagram of a receiver according to the invention.

In Fig. 1, I indicates a receiving loop with a rotating plate condenser 2 of about 500 c. m. capacity and a self-induction 3. The coil 3 is coupled with a coil 4 of a similar dimension as the coil 3. Usually it willhave a higher self-induction than the coil 3 and will correspond nearly to the self-induction of the frame plus that of the coil 3. The coil 4 leads into a high frequency multiple valve A and is connected once with the grid lead 91 of the grid 6 of the first system I. The other end of the coil is connected with the lead h, the negative end of the heated filament 5. From the anode I a wire leads to the coupling condenser H2 of the next system II and further over an anode resistance 8 of some 10,000 ohms to the lead (11 connected to the plate battery. The coupling condenser H2 is connected with the grid I2 of the system II and with the grid leak resistance In of some 10,000-100,000 ohms. The heated filament ll of the second system is joined in series with the heated filament 5 of the first system. The grid resistance In is connected to the negative end of the fila-' ment II, that is to the junction between both filaments. The other end of the filament ll leads to the lead +h and is used for the supply of the positive heated lead. The anode I3 of the system II is connected with the lead 112 a wire of which leads to the coupling condenser l5 and to the anode resistance I4. The anode resistance I4 is connected with the terminal of the anode battery. The coupling condenser [5 which has a capacity of under 200 c .in., just as the coupling condenser I I2, is connected with the lead 93 connected to grid I6 of the system III which is in the second high frequency multiple valve B. The grid [6 is connected to the high-ohmic resistance I! which is connected with the lead h, the negative end of the filament Ill. The anode l9 of the system III is connected with the coupling condenser 2| of the same dimension as the coupling condensers H2 and I5 and with the anode resistance 20. This connects to the lead as over which the anode potential is fed. The coupling condenser 2| is connected with the grid 23 of the system IV. This is connected to a high ohmic resistance 22 to the negative end of the heated filament 24, which is joined in series with the heated filament I8. The positive end of the heated filament 24 is connected to lead +71. The anode 25 of the system IV is connected to a4. From the lead (14 a connection leads to the coil 26, the self-induction of which is smaller than that of the coil 4 in the input circuit of the high frequency amplifier. To prevent an unnecessary high anode current consumption in the input circuit, which would be conditional by the low ohmic resistance of the coil 26, a resistance of about 30,000 ohms is joined behind the coil 26. But in order to procure a way for the high frequency, a capacity 3! of about 1 microfarad is joined between the coil 26 and the high ohmic resistance 30 and which capacity is connected with filament 24.

Both multiple valves A and B are paralleled with reference to the heated filament. Into the heated circuit of the second multiple valve a regulating resistance 32 is inserted which is used for regulation of the intensity of sound. The multiple valves A and B are surrounded by a metallical screen 33 which is earth-connected or which is connected with the heated circuit.

In the output circuit of the high frequency amplifier a tunable circuit is coupled with the coil 26, the tunable circuit consisting of a coil 21 and a rotating plate condenser 28 of about 500 c. m. which leads to a rectifier and a low frequency amplifier 29 which is shown only schematically. It is suitable if this rectifier and low frequency amplifier consists of a three electrode valve in which the first system is the audion, the second is a voltage amplification stage and the third is operating as the terminal stage.

In the input circuit as well as in the output circuit of the high frequency amplifier the coils 3, 4 and the coils 26 and 21 are loose coupled. Behind the low frequency amplifier 29 a loudspeaker 34 is joined.

While Fig. 1 shows more a schematic drawing of the invention, Fig. 2 is the wiring scheme of a receiver according to the invention. It contains three high frequency two-system-valves A, B and C, that means altogether six high frequency stages. I is the frame, 2 is a variable capacity of about 500 c. m., 3 is a self-induction-coil, which is coupled loose with the self-inductioncoil 4 in the high frequency amplifier entrance. Both self-inductions are enclosed into a metallic case 5. The coil 4 lies without paralleled capacity between the grid and the end of the heated filament of the first system of the highfrequency-two-electrode-valve A. Its connection is identical with that of the valve A in Fig. 1. The valve A is coupled by a resistance capacitive coupling element, consisting of an anode resistance M, a coupling condenser 55 and a grid leak resistance H with the valve 13, which is also a high frequency double valve. The valve C of the same construction as the valves A and B is coupled with another coupling element, analogous to that between the valves A and B. In its anode circuit a coil 26 is joined in series with the resistance 30, which is bridged by a condenser 3| for high frequency. In the heated circuit of the last high frequency multiple valve C there lies a variable resistance 32 for regulating the intensity of sound. The tuned circuit, which forms the entrance to the audion and to the low frequency amplifier and which consists of a coil 2'! and a capacity 28, is coupled with a coil 26. This circuit is arranged at the entrance of a threesystem-valve D, the first system of which operates as audion, whereas, for increasing the detecting action, a capacity 35 is led into the anode circuit. That capacity amounts to about 100 c. m. for it must be dimensioned so that it possesses a small resistance for high frequency and a large resistance for low frequency. The further constructions of the low frequency three-systemvalve do not show any particularly. There is used, again, a resistance capacitive coupling between the three systems which are adapted to the low frequency amplification. A loudspeaker 34 is arranged in the anode circuit of the last system of the low frequency three-system-valve and which is bridged by a capacity 36 of suitable dimension. The capacities 31. 3B and 39 are contact capacities to prevent reactions over the conductions. They amount to about 1 microfarad.

I claim:

1. In a resistance-coupled high-frequency amplifier an amplifying electrode system containing a filament, a grid and plate, a grid leak resistance connected to said grid on one side and to said filament on the other side, a coupling condenser connected on one side to that side of the grid leak resistance that is connected to the grid and on the other side to a high ohmic resistance in the order of 2,000 to 100,000 ohms, arranged in the plate circuit of a preceding amplifying arrangement, the first cited electrode system, the resistances and the coupling condenser being so dimensioned that for high frequencies the capacitive resistance of the coupling condenser is smaller than the grid circuit resistance of said amplifying electrode system, whereas for low frequencies the capacitive resistance of said coupling condenser is greater than the grid circuit resistance of said amplifying electrode system.

2. In a resistance-coupled high-frequency amplifier an amplifying electrode system containing a filament, a grid and plate. a grid leak resistance connected to said grid on one side and to said filament 0n the other side, a coupling condenser connected on one side to that side of the grid leak resistance that is connected to the grid and on the other side a high ohmic resistance in the order of 2,000 to 100,000 ohms arranged in the plate circuit of a preceding amplifying arrangement, the capacity of said grid blocking condenser being less than 200 c. m.

3. In a resistance-coupled high-frequency amplifier an amplifying electrode system containing a filament, a grid and plate, a grid leak resistance connected to said grid on one side and to said filament on the other side, a coupling condenser connected on one side to that side of the grid leak resistance that is connected to the grid and on the other side to a high ohmic resistance in the order of 2,000 to 100,000 ohms, arranged in the plate circuit of a preceding amplifying arrangement, the first cited electrode system, the

resistances and the coupling condenser being so dimensioned that for high frequencies the capacitative resistance of the coupling condenser is smaller than the grid circuit resistance of said amplifying electrode system, whereas for low frequencies' the capacitative resistance of said coupling condenser is greater than the grid circuit resistance of said amplifying electrode system, said first system beingthe first system of a double valve and said preceding amplifying arrangement being also a double valve, each of said double valves containing two amplifying electrode systems and a set of coupling elements, connecting said two electrode systems in cascade, said coupling elements being arranged together with both amplifying electrode systems within one common vacuum bulb.

4. In a resistance-coupled high-frequency amplifier an amplifying electrode system containing a filament, a grid and plate, a grid leak resistance connected to said grid on one side and to said filament on the other side, a coupling condenser connected on one side to that side of the grid leak resistance that is connected to the grid and on the other side a high ohmic resistance in the order of 2,000 to 100,000 ohms arranged in'the plate circuit of a preceding amplifying arrangement, the capacity of said grid blocking condenser being less than 200 c. m., said first system being the first system of a double valve and said preceding amplifying arrangement being also a double valve, each of said double valves containing two amplifying electrode systems and a set of coupling elements, connecting said two electrode systems in cascade, said coupling elements being arranged together with both amplifying electrode systems within one common vacuum bulb.

5. In a resistance-coupled high-frequency amplifier an amplifying electrode system containing a filament, a grid and plate, a grid leak resistance connected to said grid on one side and to said filament on the other side, a coupling condenser connected on one side to that side of the grid leak resistance that is connected to the grid and on the other side to a high ohmic resistance arranged in the plate circuit of a preceding amplifying arrangement, the capacity of said grid blocking condenser being less than 200 c. m., while said plate resistance amounts from 2,000 to 100,000 ohms and said. grid leak resistance amounts from 6,000 to 300,000 ohms, the ratio between said grid leak resistance and said plate resistance being in the order of about 3:1, said first system being the first system of a double valve and said preceding amplifying arrangement being also a double valve, each of said double valves containing two amplifying electrode systems and a set of coupling elements, connecting said two electrode systems in cascade, said coupling elements being arranged together with both amplifying electrode systems within one common vacuum bulb.

MANFRED VON ARDENN E. 

